JP6634921B2 - Doors for vehicles - Google Patents

Description

  The present invention relates to a vehicle door. More specifically, the present invention relates to a door for an automobile.

  Automotive doors are mainly manufactured by combining a door inner panel and a door outer panel. Car doors have a role in ensuring passenger safety. Therefore, a high strength is required for a door of an automobile.

  The door inner panel constituting the door is formed by pressing a metal plate such as a steel plate. Generally, since the shape of the door inner panel is complicated, the metal plate may be largely deformed. In this case, cracks, wrinkles, and the like may occur in the formed door inner panel. Therefore, a metal plate having high workability is used as a material of the door inner panel. A metal plate with high workability has low strength. Therefore, a reinforcing member such as a door impact beam is attached to the door inner panel.

  The structure of an automobile door is disclosed in Japanese Patent Application Laid-Open Nos. 2015-113053 (Patent Document 1), Japanese Patent Application Laid-Open No. 2005-212598 (Patent Document 2), and Japanese Patent Application Laid-Open No. 2006-96205 (Patent Document 3).

  The door disclosed in Patent Literature 1 includes a door inner panel and two door impact beams attached to the door inner panel. In the door of Patent Literature 1, two door impact beams bear a collision load from the side of the vehicle. Therefore, the collision load applied to one door impact beam is reduced. Patent Literature 1 describes that the strength of the door is thereby improved.

  The door disclosed in Patent Literature 2 includes a door inner panel and two door impact beams (guard bars) attached to the door inner panel. One door impact beam is curved and the other door impact beam is straight. When a collision load is applied to the door of Patent Literature 2 from the side of the vehicle, a compression force is generated in the curved door impact beam, and a tensile force is generated in the linear door impact beam. Patent Literature 2 discloses that the strength of the door can be maintained high from the start of the collision load to the end of the load.

  The door disclosed in Patent Literature 3 includes a door inner panel, two door impact beams, and a reaction force generating mechanism that connects the two door impact beams. In the door of Patent Document 3, a collision load from the side of the vehicle is applied to the reaction force generating mechanism. The reaction force generating mechanism changes the direction of the collision load in the vehicle left-right direction to the vehicle up-down direction. The vertical load is borne by the two door impact beams. Patent Literature 3 describes that the strength of the door is thereby improved.

JP 2015-113053 A JP 2005-212598 A JP 2006-96205 A

  However, each of the doors of Patent Documents 1 to 3 includes two door impact beams in order to increase the strength of the door. Therefore, the doors of Patent Documents 1 to 3 are heavy and costly. Further, all of the doors of Patent Documents 1 to 3 have low production efficiency because two door impact beams are attached to the door inner panel.

  It is an object of the present invention to provide a lightweight and strong door.

  A door according to an embodiment of the present invention includes a door inner panel and one door impact beam. The door inner panel is made of a metal plate. The tensile strength of the door inner panel is 1200 MPa or more. Both ends of the door impact beam are joined to the door inner panel. The door inner panel includes a linear recess intersecting the door impact beam. The recess projects toward the door impact beam.

  The door according to the invention is light and strong.

FIG. 1 is a perspective view of a door inner panel and a door impact beam of the present embodiment. FIG. 2 is a sectional view of the door of the present embodiment. FIG. 3 is a sectional view of the door inner panel and the door impact beam of the present embodiment at the time of a side collision. FIG. 4 is a perspective view of a door inner panel having a door impact beam different from that of FIG. 1 and a door impact beam. FIG. 5 is a cross-sectional view schematically showing a hot stamping device for manufacturing the door inner panel of the present embodiment. FIG. 6 is a cross-sectional view showing a step of sandwiching the blank material S between the blank holders. FIG. 7 is a cross-sectional view showing a state when the pushing by the second punch is completed. FIG. 8 is a cross-sectional view showing a state when the pushing by the first punch is completed. FIG. 9 is a cross-sectional view showing a state during press working by a general hot stamping apparatus.

  The door according to the present embodiment includes a door inner panel and one door impact beam. The door inner panel is made of a metal plate. The tensile strength of the door inner panel is 1200 MPa or more. Both ends of the door impact beam are joined to the door inner panel. The door inner panel includes a linear recess intersecting the door impact beam. The recess projects toward the door impact beam.

  When a collision load is applied to the door of this embodiment from the side of the vehicle, the door impact beam is deformed toward the door inner panel. The recess provided in the door inner panel intersects with the door impact beam. Therefore, when the deformation of the door impact beam progresses, the door impact beam hits a concave portion of the door inner panel. As a result, a part of the collision energy given to the door impact beam is absorbed by the door inner panel. The recess increases the second moment of area of the door inner panel. Therefore, even if a part of the collision energy is borne by the door inner panel, the door inner panel is not easily damaged. Further, such a high strength door inner panel is formed by, for example, hot stamping. The tensile strength of the door inner panel is 1200 MPa or more. Since the strength of the door inner panel is sufficiently high, the strength of the door is high even if the door impact beam, which is a separate component, is made of a material having a simple shape and low strength. Thus, the door of the present embodiment has high strength even with a single door impact beam. Therefore, the weight of the door can be reduced, and the cost of the door can be reduced.

  Both ends of the door impact beam are attached to the door inner panel. Therefore, the center of the door impact beam is most easily deformed and easily broken. Therefore, in order to increase the strength of the door, it is efficient to suppress the deformation of the center of the door impact beam. Therefore, the recesses preferably intersect at the center of the door impact beam.

  The intersection angle between the recess and the door impact beam is preferably 10 ° or more and 90 ° or less. If the intersection angle is less than 10 °, the contact area between the recess and the door impact beam is difficult to stabilize.

  When the bending strength of the door impact beam is stronger than the bending strength of the door inner panel, the door inner panel may be greatly deformed following the deformation of the door impact beam. In this case, the door impact beam hardly hits the recess of the door inner panel. Therefore, the deformation of the door impact beam may not be sufficiently suppressed. Therefore, the total plastic bending moment of the door impact beam is preferably smaller than the total plastic bending moment of the door inner panel.

  Preferably, the door impact beam includes a longitudinally extending ridge or depression. The ridges and depressions increase the second moment of area of the door impact beam. Therefore, the cost of the door impact beam can be further reduced. As a result, the cost of the door can be reduced.

  The door inner panel preferably has a top plate, an opening, and a vertical wall. The top plate is polygonal. The opening is formed in the top plate. The vertical wall portion extends from at least two adjacent sides of the side of the top plate portion. At least one set of each of the adjacent vertical wall portions among the vertical wall portions includes a step portion. The door inner panel faces body parts such as pillars and seals the inside of the vehicle. When the adjacent vertical wall has a step, the airtightness in the vehicle can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts have the same reference characters allotted, and description thereof will not be repeated. Hereinafter, a case where the door of the present embodiment is a side door of an automobile will be described as an example.

  FIG. 1 is a perspective view of a door inner panel and a door impact beam of the present embodiment. With reference to FIG. 1, the door inner panel 1 includes a top plate 2, a vertical wall 5, a step 6, and a flange 7. The door impact beam 9 includes both ends 17. Both ends 17 of the door impact beam 9 are joined to the door inner panel 1. The joining method is, for example, spot welding. Further, both ends 17 of the door impact beam 9 may be joined to the door inner panel 1 via a bracket. FIG. 1 shows a case where both end portions 17 of the door impact beam 9 are joined to the step portion 6 of the door inner panel 1. However, the joining position of both ends 17 of the door impact beam 9 is not limited to this case. Both ends 17 of the door impact beam 9 may be joined to, for example, the flange 7.

  The door inner panel 1 includes a linear recess 3 intersecting with the door impact beam 9. More specifically, the recess 3 is provided in the top plate 2. The recess 3 protrudes from the top plate 2 toward the door impact beam 9. When a collision load is applied from the side of the vehicle (hereinafter, also referred to as a side collision), the door impact beam 9 hits the recess 3 of the door inner panel 1. Thereby, a part of the collision energy given to the door impact beam 9 is borne by the door inner panel, so that the collision energy borne by the door impact beam 9 is reduced. This will be described in detail with reference to FIGS.

  FIG. 2 is a sectional view of the door of the present embodiment. FIG. 2 is a cross-sectional view as viewed from the vehicle front-rear direction. The door of the present embodiment includes a door inner panel 1, a door impact beam 9, and a door outer panel 16. As shown in FIG. 2, the door impact beam 9 is disposed between the door outer panel 16 and the door inner panel 1. The storage position of the door glass in the door may be between the door impact beam 9 and the door outer panel 16 or between the door impact beam 9 and the recess 3 of the door inner panel 1. Further, the door impact beam 9 may be in contact with the recess 3 of the door inner panel 1, or they may be joined by an adhesive or welding.

  In a side collision, the collision load P is first applied to the door outer panel 16. The door outer panel 16 is deformed and enters the inside of the vehicle (the door inner panel 1 side). Next, the door outer panel 16 hits the door impact beam 9. As a result, a collision load is applied to the door impact beam 9 and the door impact beam 9 is deformed toward the door inner panel 1.

  FIG. 3 is a sectional view of the door inner panel and the door impact beam of the present embodiment at the time of a side collision. Referring to FIG. 3, door impact beam 9 strikes recess 3 of door inner panel 1. This is because the recess 3 projects toward the door impact beam 9. Thereby, the deformation of the door impact beam 9 is suppressed by the recess 3. A part of the collision energy due to the collision load P applied to the door impact beam 9 is given to the door inner panel 1. Thereby, the collision energy given to the door impact beam 9 is reduced.

  In short, since a part of the collision energy is given to the door inner panel 1, even if the strength of the door impact beam 9 is reduced, the door impact beam 9 is hardly damaged. Therefore, in the door of the present embodiment, the shape of the door impact beam 9 can be simplified, and a material having low strength can be adopted for the door impact beam. Thus, the door can be reduced in weight while maintaining the strength of the door, and the cost of the door can be reduced. For example, as shown in FIG. 1, in the door of the present embodiment, the strength of the door can be maintained even with one door impact beam 9.

  Further, by providing the concave portion 3 in the top plate portion 2 of the door inner panel 1, the second moment of area of the top plate portion 2 increases. Further, the tensile strength of the door inner panel 1 is 1200 MPa or more. Even if collision energy is applied to the door inner panel 1 from the door impact beam 9, the door inner panel 1 is hardly damaged. Therefore, the safety of the passenger is ensured.

  As shown in FIG. 1, both ends 17 of the door impact beam 9 are joined to the door inner panel 1. Therefore, the amount of deformation at the intermediate position between both ends 17 of the door impact beam 9 (hereinafter also referred to as the center of the door impact beam) is the largest. In other words, the center of the door impact beam 9 is most easily damaged. As described above, when the door impact beam 9 hits the concave portion 3, the deformation of the door impact beam 9 is suppressed. Therefore, the recesses 3 preferably intersect at the center of the door impact beam 9. Here, an acute angle among the angles formed by the concave portion 3 and the door impact beam 9 on the horizontal plane is referred to as an intersection angle θ.

  Actually, the load applied to the door impact beam 9 is not uniformly distributed in the width direction of the door impact beam 9. Therefore, if the intersection angle θ is less than 10 °, when the door impact beam 9 hits the concave portion 3, the contact area between the concave portion 3 and the door impact beam 9 is easily moved and is not easily stabilized. For example, assume that the intersection angle θ = 0 °. In this case, even if the door impact beam 9 hits the recess 3, the door impact beam 9 slides and it is difficult to maintain contact with the recess 3. Therefore, the intersection angle θ between the recess 3 and the door impact beam 9 is preferably 10 ° or more and 90 ° or less.

  Further, when the strength of the door impact beam 9 is higher than the strength of the door inner panel 1, when the door impact beam 9 is deformed, the door inner panel 1 may be deformed. In this case, the concave portion 3 of the door inner panel 1 is deformed in a direction away from the door impact beam 9. Therefore, the door impact beam 9 does not easily come into contact with the recess 3. Therefore, the strength of the door impact beam 9 is preferably lower than the strength of the door inner panel 1. More specifically, the total plastic bending moment of the door impact beam 9 is preferably smaller than the total plastic bending moment of the door inner panel 1. Here, the total plastic bending moment refers to a bending moment applied to an arbitrary cross section of a component when the cross section reaches a full plastic state.

  Hereinafter, the door impact beam and the door inner panel of the present embodiment will be described in detail.

[Door impact beam]
FIG. 1 shows a case where the door impact beam 9 is made of a metal plate. In this case, the door impact beam 9 can be easily obtained by pressing a metal plate. FIG. 1 shows a case where the door impact beam 9 has a depression 18. The depression 18 extends in the longitudinal direction of the door impact beam 9. The depression 18 increases the second moment of area of the door impact beam 9. The door impact beam 9 may have a ridge instead of the depression 18. The bump also increases the second moment of area of the door impact beam 9. Thereby, the strength of the door impact beam 9 is improved. When the door impact beam 9 has sufficient strength, the door impact beam 9 does not have to have the depression 18 or the raised portion.

  FIG. 4 is a perspective view of a door inner panel having a door impact beam different from that of FIG. 1 and a door impact beam. FIG. 4 shows a case where the door impact beam 9 is made of a metal tube. In this case, the door impact beam 9 is joined to the door inner panel 1 via the bracket 8. The joining method is, for example, arc welding.

  Regardless of whether the door impact beam 9 is a metal plate or a metal tube, the material of the door impact beam 9 is preferably steel. This is from the viewpoint of adjustment of strength and the like, cost and the like. However, the material of the door impact beam 9 is not limited to steel, and may be another metal. Other metals are, for example, aluminum, aluminum alloy, multi-layer steel, titanium, magnesium and the like. Other than metals, there are CFRP (carbon fiber reinforced plastic) and resin. Further, the tensile strength of the door impact beam 9 is preferably 1200 MPa or more. This is for absorbing the collision energy at the time of a side collision and ensuring the safety of the occupant.

[Door inner panel]
Referring to FIG. 4, the door inner panel 1 of the present embodiment is made of a metal plate. The metal plate as the material of the door inner panel 1 is, for example, a steel plate, an aluminum plate, an aluminum alloy plate, a multilayer steel plate, a titanium plate, a magnesium plate, or the like. In the present embodiment, a case where the thickness of the metal plate is constant will be described. Therefore, the thickness of the door inner panel 1 is also constant over the entire area. However, strictly speaking, a slight increase or decrease in the plate thickness occurs by press molding.

  The planar shape of the top plate 2 is a polygon. The polygon may be, for example, a quadrangle or a pentagon. The corners of the polygon may be rounded. FIG. 4 shows a case where the planar shape of the top plate 2 is a pentagon as an example. In the door inner panel 1, the side of the top plate 2 on the upper side of the vehicle forms a belt line BL. The belt line BL is on the entrance side of a window (not shown). Therefore, the vertical wall portion 5 does not exist on the belt line BL.

  The vertical wall portion 5 extends from at least two or more sides of the outer side of the top plate portion 2. In FIG. 4, as an example, a case where the vertical wall portion 5 extends from four sides 2A, 2B, 2C, and 2D excluding the side on the upper side of the vehicle (belt line BL) among the five sides outside the top plate portion 2 is shown. Show. The vertical wall portion 5 is opposed to a main body component (a pillar, a side sill, or the like) of the vehicle, and enhances the hermeticity of the vehicle. Therefore, the vertical wall portion 5 preferably extends from each of two or more adjacent sides of the top plate portion 2. When the vertical wall portions 5 extend from two or more adjacent sides of the top plate portion 2, the vertical wall portions extending from each side are also adjacent. FIG. 4 shows, as an example, a case where the vertical wall portion 5 extends perpendicularly to the top plate portion 2. However, the vertical wall portion 5 need not be strictly perpendicular to the top plate portion 2.

  The step portion 6 extends outward from the vertical wall portion 5A connected to the top plate portion 2. The outer edge of the step portion 6 is connected to the vertical wall portion 5B connected to the flange portion 7. FIG. 4 shows a case where the step portion 6 is parallel to the top plate portion 2 as an example. However, the step 6 does not have to be strictly parallel to the top plate 2. FIG. 4 shows, as an example, a case where four adjacent vertical wall portions 5 have a step portion 6. That is, there is a case where there are three sets of the adjacent vertical wall portions 5 and all three sets have the step portion 6. FIG. 4 shows a case where one step portion 6 is provided on the vertical wall portion 5. However, the number of the step portions 6 is not limited to one, and may be plural. The step 6 faces the pillar B of the vehicle body and the like, and seals the inside of the vehicle. A sealing member is disposed between the stepped portion 6 and the pillar or the like in order to enhance the airtightness in the vehicle.

  FIG. 4 shows a case where the door inner panel 1 has the stepped portion 6. However, the door inner panel 1 may not have the stepped portion 6. Even if the door inner panel 1 does not have the stepped portion 6, the stepped portion 6 is unnecessary if the inside of the vehicle is sufficiently sealed. When the door inner panel 1 has no stepped portion 6, the door impact beam 9 is joined to the flange 7 of the door inner panel 1.

  The door inner panel 1 may have an opening 4. Parts such as speakers are attached to the opening 4.

  When the door inner panel 1 is made of a steel plate, the steel plate may be a tailored blank. Tailored blanks are broadly classified into tailored welding blanks (hereinafter, also referred to as “TWB”) and tailored rolled blanks (hereinafter, also referred to as “TRB”). TWB is obtained by integrating a plurality of types of steel plates having different thicknesses, tensile strengths, and the like by welding (eg, butt welding). On the other hand, in the case of TRB, the thickness of a steel sheet is changed by changing the interval between rolling rolls when manufacturing a steel sheet. When a tailored blank is used, the strength can be strengthened only at a necessary portion and the thickness can be reduced. Further, a door inner panel using a tailored blank can also be applied to a door inner panel for an automobile. Thereby, the collision characteristics can be improved, and further reduction in weight can be expected.

  As described above, the door inner panel of the present embodiment bears a part of the collision energy given to the door impact beam. For this reason, the strength of the door inner panel is preferably higher. Specifically, the tensile strength of the door inner panel is 1200 MPa or more. This is because the door inner panel can absorb more collision energy as the tensile strength increases. However, a door inner panel having a high tensile strength and a complicated shape is usually difficult to mold. Specifically, a door inner panel having a complicated shape is likely to generate wrinkles, cracks, and the like during processing. The complicated shape includes, for example, a shape in which an adjacent vertical wall portion 5 has a step portion 6 like the door inner panel 1 shown in FIG. Hereinafter, an example of a method for manufacturing a door inner panel made of a steel plate and having a complicated shape having a tensile strength of 1200 MPa or more will be described.

[Production method]
The method for manufacturing a door inner panel according to the present embodiment includes a preparation step, a heating step, and a press forming step by hot stamping. In the preparation step, a blank material made of a steel plate is prepared. In the heating step, the blank is heated. In the press forming process, the heated blank is pressed and, at the same time, the formed door inner panel is quenched. In the press forming step of the present embodiment, a hot stamping device is used as a press working device.

[Hot stamping device 10]
FIG. 5 is a cross-sectional view schematically showing a hot stamping device for manufacturing the door inner panel of the present embodiment. Referring to FIG. 5, hot stamping apparatus 10 includes punch 11 and blank holder 14 as an upper die, and die 15 as a lower die.

  The punch 11 includes a first punch 12 and a second punch 13. The first punch 12 is formed with the shape of the top plate of the door inner panel. The shape of the step portion of the door inner panel is formed in the second punch 13. The punch 11 pushes the blank material S into the die 15 to form a door inner panel.

  The blank holder 14 is arranged outside the second punch 13. The blank holder 14 faces the die 15. The blank holder 14 sandwiches the blank material S between the blank holder 14 and the die 15.

  The die 15 faces the first punch 12 and the second punch 13.

  The die 15 and the first punch 12 form the top plate 2 of the door inner panel 1 shown in FIG. The die 15 and the second punch 13 form the step 6 of the door inner panel 1 shown in FIG. The die 15 and the blank holder 14 form the flange 7 of the door inner panel 1 shown in FIG. Hereinafter, each step of the manufacturing method of the present embodiment will be described.

[Preparation process]
In the preparation step, a blank material made of a steel plate is prepared. The steel sheet of the door inner panel of the present embodiment preferably contains carbon (C): 0.11% or more by mass%. When the steel sheet contains 0.11% or more of carbon, the strength of the door inner panel after hot stamping can be increased.

[Heating process]
In the heating step, the blank is heated by a heating device (not shown). The blank is preferably heated above the A1 transformation point of the material. More preferably, the blank is heated above the A3 transformation point. In hot stamping, the formed door inner panel is quenched at the same time as the blank material is press-formed. If the blank material is heated to the point A1 or more, the metal structure of the quenched door inner panel becomes martensite and the strength increases. The heating temperature is, for example, 700 to 900C. The heating temperature is appropriately set depending on the material, the degree of difficulty in molding, and the like. In hot stamping, since a blank material is heated and softened, a complicated shape can be formed.

[Press molding process]
6 to 8 are cross-sectional views schematically showing a press forming step of the present embodiment. FIG. 6 shows a step of sandwiching the blank material S between the blank holders 14. FIG. 7 shows a state when the pushing by the second punch 13 is completed. FIG. 8 shows a state when the pushing by the first punch 12 is completed.

  Referring to FIG. 6, the heated blank S is placed in a hot stamping apparatus 10. After the blank S is placed, the slide of the hot stamping device is lowered. Thus, the blank material S is sandwiched between the blank holder 14 and the die 15. However, the distance between the blank holder 14 and the die 15 is preferably larger than the thickness of the blank material S. That is, a gap is provided between the blank material S and the blank holder 14. The size of the gap is, for example, 0.1 mm. When the blank S is brought into contact with the blank holder 14, a portion of the blank S that contacts the blank holder 14 is cooled before the blank S is pressed. Therefore, since the cooling rate of the blank S is partially different, the strength of the molded article is different from part to part. Therefore, it is preferable that a slight gap is provided between the blank holder 14 and the blank material S.

  Referring to FIG. 7, when the slide is further lowered, blank material S is drawn by punch 11 and die 15. FIG. 7 shows a case where the first punch 12 is located at the same height as the second punch 13 when the pressing of the blank material S by the second punch 13 is completed. That is, the case where the pushing of the blank S by the first punch 12 starts at the same time when the pushing of the blank S by the second punch 13 is completed.

  However, when the pressing of the blank material S by the second punch 13 is completed, the position of the height of the first punch 12 is not limited to the position of the same height as the second punch 13. At this time, the height position of the first punch 12 may be higher or lower than the second punch 13. That is, the pushing of the blank S by the first punch 12 may be started after the pushing of the blank S by the second punch 13 is completed. In addition, before the pressing of the blank S by the second punch 13 is completed, the pressing of the blank S by the first punch 12 may start. In any case, the pressing by the first punch 12 is not completed before the pressing by the second punch 13. It is sufficient that the blank material is suppressed by the blank holder and the die before the forming of the second punch is completed.

  Referring to FIG. 8, after the pressing by the second punch 13 is completed, the first punch 12 is lowered, and the blank S is drawn. At this time, the portion of the blank S pressed by the second punch 13 is restrained by the second punch 13. Thereby, wrinkles and the like generated near the step portion of the door inner panel can be suppressed. Hereinafter, this point will be described in detail.

[Suppression of cracks and wrinkles]
FIG. 9 is a cross-sectional view showing a state during press working by a general hot stamping apparatus. FIG. 9 shows a part of a die of a general hot stamping apparatus in an enlarged manner. Referring to FIG. 9, in hot stamping apparatus 200, punch 210 is not divided. Therefore, when the punch 210 is lowered, the portion S1 of the blank S is not restrained by the punch 210 and the die 220. That is, the portion S1 of the blank material S does not contact the punch 210 and the die 220.

  In hot stamping, the blank is cooled by contact between the blank and a punch, die or the like. Therefore, at the stage shown in FIG. 9 during the press working, the part S1 of the blank S is not cooled. A portion S1 of the blank S is cooled when the punch 210 is further pushed in from the position shown in FIG. In short, when the door inner panel in which the vertical wall portion is provided with the step portion is formed by the punch 210 in which the shape of the top plate portion and the step portion of the door inner panel are integrally formed, a part S1 of the blank material S becomes Cools later than other parts.

  If the cooling of the blank S is partially delayed, the strength and ductility of the blank S may be partially different. In this case, wrinkles and the like are likely to be generated in the door inner panel to be formed. As shown in FIGS. 1 and 4, when the vertical wall portion 5 adjacent to the door inner panel 1 has the step portion 6, wrinkles and the like are particularly likely to occur. If the strength of the door inner panel after molding is high, wrinkles and the like are more likely to occur.

  As shown in FIG. 5, the method for manufacturing a door inner panel according to the present embodiment uses a hot stamping device 10 having a first punch 12 and a second punch 13. Thereby, the top plate 2 and the step 6 of the door inner panel 1 as shown in FIGS. 1 and 4 are formed by separate punches. In addition, the pressing by the second punch 13 is completed before the pressing by the first punch 12. As a result, when one punch forms the top plate 2, the other punch suppresses the step 6 of the door inner panel 1. Therefore, when the top plate 2 is formed, the unconstrained portion of the blank material is reduced, and wrinkles and the like of the door inner panel can be suppressed.

  In the above description, the case where the door of this embodiment is a side door for an automobile has been described. However, the door of the present embodiment is not limited to a side door for an automobile. The door of this embodiment can be applied to a rear door and the like.

  The embodiments of the present invention have been described above. However, the above-described embodiment is merely an example for implementing the present invention. Therefore, the present invention is not limited to the above-described embodiments, and can be implemented by appropriately modifying the above-described embodiments without departing from the spirit thereof.

DESCRIPTION OF SYMBOLS 1 Door inner panel 2 Top plate part 3 Concave part 4 Opening part 5 Vertical wall part 6 Step part 7 Flange part 8 Bracket 9 Door impact beam 10 Hot stamping device 12 1st punch 13 2nd punch 14 Blank holder 15 Die 16 Door outer panel 17 Both ends of door impact beam 18 Depressed portion BL Belt line S Blank material P Impact load θ Crossing angle

Claims (5)

A door inner panel made of a metal plate and having a tensile strength of 1200 MPa or more;
One door impact beam having both ends joined to the door inner panel,
The door inner panel includes a linear recess crossing the door impact beam,
The recess protrudes towards the door impact beam,
The door, wherein a total plastic bending moment of the door impact beam is smaller than a total plastic bending moment of the door inner panel . The door according to claim 1,
The door, wherein the recesses intersect at a center of the door impact beam. The door according to claim 1 or claim 2,
A door, wherein an intersection angle between the concave portion and the door impact beam is 10 ° or more and 90 ° or less. The door according to any one of claims 1 to 3 ,
A door, wherein the door impact beam includes a longitudinally extending ridge or depression. The door according to any one of claims 1 to 4 ,
The door inner panel includes a polygonal top plate, an opening formed in the top plate, and a vertical wall extending from at least two adjacent sides of the sides of the top plate. The door, wherein at least one set of the vertical wall portions of the vertical wall portions includes a step portion, at least one set of the vertical wall portions adjacent to each other.

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